Ak74u mosfet+ trigger unit

[Kash]

So I got an E&L aks74un which is fantastic in almost every way.

 

My only very minor whinge is the lack of mosfet and quite long trigger pull.

 

Since a v2 mosfet unit like a gate titan wont fit, does anyone have any suggestions, bear in mind its the smg so, minimal space for any extra outside the gearbox parts.. The only thing ive found was a chimera, but stock is like unicorn tears it seems.

 

And while im here, anyone got any experience with the tech dep at patrolbase or op7 in sheffield dunno it I dare crack open a gearbox in a gun this expensive

[Lozart]

As you say it's not a V2 gearbox. It's a V3 gearbox which is known in general for having a long trigger pull. It's just down to the design I'm afraid. 

 

BTC Chimera V3 is even more like unicorn tears than the V2 and there isn't (as far as I am aware) a V3 Gate Titan yet so you're going to be limited to the more "standard" type mosfets. I had a Gate Pico in my old CYMA AKS74U and that worked well but obviously wasn't as full function as something like a BTC. Depends on whether or not you need the programmability or not.

 

As far as trigger travel goes you could look at something like this: http://www.patrolbase.co.uk/airsoft/retro-arms-ak-speed-trigger-for-v3-gearbox-type-a-green.htm#.WVocs4jyuMo 

[Kash]

I was looking at the smaller gate fets so I could go 11.1 but my main bother is the trigger pull.

 

About a month ago I saw some chimera v3s in stock at a smaller retailer I know, but when I actually thought about doing it, gone, as per usual

[Lozart]

Yeah, anything by BTC seems to disappear pretty quickly. They are great though (I have a Spectre in my SCAR).

 

As I say, without a FET that uses adjustable trigger contacts your only real bet is something like the trigger I linked to. V3 boxes just seem to have a really long pull. There was a topic on here a while back about trying to fix the length of pull on a V3, might be worth a forum search.

[Sitting Duck]

best tiny mosfet especially on a AK with battery under the cover.....

 

http://www.firestormsystems.com/shop/electronics/mosfet-switch.html

 

out of stock atm but email them, should be in stock in a week or so

should be able to cram that in up the front if your battery stick isn't too long

one of the tiniest mosfets out there and on a v3 no need to rip box open to fit

(V2's will always need opening up to rewire - unless somebody has got an army of ants working for them) 

 

As for trigger pull,always going to get that on two part triggers in v3's

wear in one/both part will greatly increase this over time but something that is common in v3's

There are trigger mods which involves shortening the pull by adding material - usually metal or very hard plastic

usually glued in place with strong epoxy glue - JB Weld & such like

it is more a project to consider if you are quite sad with a fair bit of time on your hands

It will never ever be a hairline trigger mod like some of the fancy BTC or ASCU

just can't be as the mechanics of the trolley/sear/COL need a bit of room to operate correctly

 

I'd say you probably get it about half the trigger pull maybe a little less

you basically are taking out all the slack or free space in the trigger operation

but need to slightly mod the " lug " of the trolley that the COL slips under/over in auto/semi

but still leave enough room for COL to slip under and pop the trolley off the sear 

but it takes time testing - retesting file some more, crap start again or order new switch

more glue, more filing - damn it trolley doesn't pop off the sear or reset correctly or semi not working 101%

But - if you endure all this it can work very well - but it takes a while to understand how it all works

Not really difficult, just a bit time consuming and often need to start over again first or second attempt

might need to buy another trigger switch if you balls up the trigger trolley - no biggy it is just the trolley

 

If this sounds too much then you could look to just add very thin material to the two part trigger/sear

just enough to take up some slack and where the actual trigger stops on its return

BUT the second part - the sear needs to rest in its correct place as it is part of the safety mechanism

so you can only take out any slack or wear on the trigger's resting point

hence after reducing what play you can, the next bit is adding material to actual sear/back of trolley/trim the lug etc....

plus loads and loads of testing the operation - PITA

 

TBH once more, a V2 is a bit more straight forward as you don't have the slack that the v3 has to begin with

the v3 sear is tiny thin mofo to glue material onto - but then I guess a v3 trolley stop won't snap off

(coz the stop is a chunk of metal frame not some poxy little lug that can break over time easily on most v2's)

 

Will somebody make a v3 box with a single piece trigger like a v2

or a v2 with a motor frame

 

Oh wait they did - HK33

 

 

TBH - unless you wish to rip most of your hair out - live with it I'm afraid

If a box needs a rebuild then consider it perhaps when you open her up next

If you trigger and or trolley is jumping off each other then go for it - you can often improve it with the mod

plus it is knackered atm so wtf you have to lose if you give up and buy new switch/trigger etc...

 

This is by no means a guide - you need to google that and a number of people do this a few different ways

I was merely explaining the principal yeah went way overboard as per usual

but it involves a bit of gluing - waiting, filing testing and repeat many times

then if you do get it sussed - just hope it all holds up without the glued bits coming adrift or failing on the field

 

Not that difficult but certainly not as straight forward piece of cake 5 min mod

[Kash]

1 hour ago, Sitting Duck said:

best tiny mosfet especially on a AK with battery under the cover.....

 

http://www.firestormsystems.com/shop/electronics/mosfet-switch.html

 

out of stock atm but email them, should be in stock in a week or so

should be able to cram that in up the front if your battery stick isn't too long

one of the tiniest mosfets out there and on a v3 no need to rip box open to fit

(V2's will always need opening up to rewire - unless somebody has got an army of ants working for them) 

 

Probably a stupid question, but how exactly do i wire in a mosfet without needing to open it up? 

 

The trigger mech really that diff on a V3?

 

only even been in a v2

[Sitting Duck]

52 minutes ago, Kash said:

Probably a stupid question, but how exactly do i wire in a mosfet without needing to open it up? 

 

The trigger mech really that diff on a V3?

 

only even been in a v2

 

A walk in the park compared to v2...

ya motor wires are external - all outside the box

and the trigger wiring points should be as well

covered in shrinktube after being soldered onto external points

(or just splice & join onto existing wire)

Either rewire with dedicated thin switch wiring & dedicated thicker motor wires

or join the seperate wires at switch to same contact & run a thin signal wire back to mosfet

usual mosfet wiring options etc... blah blah blah....

 

No real need to open up a v3 really to fit a mosfet

no rewiring around the the motor/pinion entry point hoping to close up the box without pinching thicker wire etc...

 

As for trigger - yeah just a " bit " different to a v2...

 

 

2 parts that slip together and this extra linkage creates some slack

plus it can be bastid to refit at first, but you get the knack like the AR Latch & v2 trigger

 

both v2's & v3's have their flaws

The v3 motor cage is what I love the most - the mosfet issue is no biggy to open a v2

even the HK33 would need to be opened up to wire in a mosfet

So I guess the v3 wins - just the excessive trigger play lets it down I guess

 

If you have not been into a v3 before and you got a nice gun then leave opening her up for trigger

if you have some common sense then a mosfet is easy peasy on a v3

just make sure you get the fire select linkage back in place correctly

no need to rip box open until it needs it

mosfet fairly straight foward - watch some guides on gearbox removal and the fire select stuff

should be a doddle if you got a bit of common sense & take your time

best results - rewire with better wiring to motors and deans when fitting a mosfet

but if existing wiring is ok and decent reusing the stock wire to the motor will make it easier/quicker

just make it neat and short free = walk in the park